Method of producing cinematograph films



Jan. 14, 1941. c. RUDKlN 2,228,643

I METHOD OF PRODUCING CINEMATOGRAPH FILMS Filed Jan. 23, 1939 4 Sheets-Sheet l Attorney uuunn nugunnun Jan. 14-, 1941- L. c. RUDKIN METHOD OF PRODUCING CINEMATOGRAPH FILMS Filed Jan. 23, 1939 4 Sheets-Sheet 2 IN WIN TOR Lewis 6. Rudkin Jan. 14,1941. L. c. RUDKIN 2,

METHOD OF PRODUCING CINEMATOGR APH FILMS- I Filed Jan. 23, 1959 4 Sheets-Sheet 3 Fig.6.

I noentor MMM Attorn ey Jan. 14, 1941; 1.. c. RUDKIN' METHODOF PRODUCING CI NEMATQGRAPE FILMS Filed Jan. 23, 1939 I 4 Sheets-Sheet 4 Inventor Attorney 5 news reel the sound occuring at the time when desired relative volumes of sound required from tract: comprising a. number or tracirausually two.

Patented Jan. 14, 1941 Lewis Charles Bodkin, Streatham, London,

England Application .IanuaryZS, 1939, Serial No. 252,49

, In Great Britain January 27, 1938 .5 Claims. (Cl. 274-46) This invention relates to methods of and appa ratus for recording sound on clnematograph films. Often two separate sounds have to be reproduced from a single strip of films For example, in a the pictures were taken has frequently to hereproduced simultaneously with the voice of a commentator, the commentators remarks having been recorded later than the pictures and corresponding sound. So far as I am aware, the two separate sound recordings have always been mixed, in such a case, so that, on the master negative and the prints taken therefrom; there is a single variable density or variable area. sound track constituted by the resultant oi the two separate recordings. The gradations of density or the form of the black and white parts in this resultant have components, due to the two recordings, that are mixed in such a way that the volume of sound due to one recording is reproduced inrelation to the volume or sound due to the other recording in a predetermined manner, and the resultant tract; is often such that one volume at first predominates and then dimmhes, whilethe other volume of sound becomes predominant.

According to the present invention a record of two or more sounds is produced on a cinematograph film by printing thereon separate sound tracks representing, respectively, the separate sounds, in parallel to be reproduced simultanecusly. One advantage of this method'is that one of the tracks may he a variable density track while another is a variable area track. Such tracks cannot be mixed to provide a single resultant, errcent electrically, but there is no dimculty in reproducing sound simultaneously from the two ciliferent traclrs in parallel.

The tracks are'printed from tracks already recorded and, very conveniently, the widths of the, tracks being printed may be varied relatively to those already recorded in accordance with the the printed tracks at the various points along the lengths thereof. advantageously, the printed tracks may lie between parallel lines, the perpendicular distance between which is equal to the maximum width of the tracks already recorded. lhus, the tracks printed in parallel occupy a width that is no greater than the width of the single track that has hitherto, so far as I am aware, always been provided, and no special prolooting apparatus is necessary for the composite in parallel.

Where one of the tracks being printed is a variable density track, its width may be varied by adjusting the width of an aperture to expose more or less of the width of the associated track which has already been recorded. In the caseo! a variable area track, on the other hand, its width may be varied by adjusting the angle subtended between the plane of the film being printed and the plane of the track that has already been recorded,

it being understood that, in this particular arrangement, an image of the last-mentioned track l is projected onto the film being printed. This arrangement'is also suitable for variable density tracks. a

The width of each track being printed may be controlled-by a. grading strip which is caused to travel in timed relationship with the film being printed, through the apparatus for effecting the printing. A method of producing the grading strip is to pass the tracks already recorded as to sever from the strip a narrower strip, to serve as the grading strip, having a cam edge.

In order that the invention may be clearly understood and readily carried into efiect, certain methods and atusin accordance therewith will now be described icy way of example with reference to the accompanions diagrammatic drawings, in which:

Figures 1 and ii are respectively a sectional side elevation and a sectional plan of apparatus for printing two variable density sound tracks, Fig me i being a section on the line 1-1 in Figure 2,. and Figure 2 being a section on the line liI--II in Figure 1; l I

Figure 3 is a perspective view of another form of apparatus for use in printing sound tracks; .40

Flo l is a sectional plan showing certain parts of the apparatus of Figure 3;

Figure 5 is a view similar to Figure l, but show- I ing one of the parts in another position that it can take up during the operation of theapparatusy Figure 6 is a part sectional plan of a third form of apparatus for use in printing sound tracks; and

Figure '7 is a perspective view of apparatus for use in controlling thehpparatus shown in the. preceding figures.

Referring to Figures 1 and 2, a strip l 01 cinematograph him, which is to constitute a master negative, is drawn oil a spool 2 and woundupon a spool 3. The film may already have pictures printed on the path or space 4 or it may receive the pictures in a subsequent operation. Between the two spools, the film I passes beneath two films 5 5' and 6 bearing positive records of sound tracks and it is from these recordsthat a pair of negative sound tracks I and 3 are printed on the film l. The records on the films 5 and 6 are variable density tracks; that is to say, the tracks are 10 of constant width and-the sound is represented by gradations of light'jand shade. The total width of the sound tracks I and 3, that is to say the distance between theparallel base lines 3 and I3, is

equal to the width of eachof the tracks on the strips 6 and 6 land is the standard width of a variable' density sound track as used in ordinary cinematograph practice. Therefore, to print the two separate tracks between the lines 3 and it, it is necessary to expose to the film i only part of the width of each of the tracks on the films 5 and 8. This is done by passing the film 5 between the film land a plate II formed with a controllable aperture i2. similarly, the film 3 is passed between 'the film I and a plate I3 formed with a 35 relationship. However, in practice it is often desirable to arrange for one sound to become dominant, while the other diminishes, and then for the latter sound to become dominant. For example, often when music and speech are to be reproduced 40 simultaneously, first one and then the other has to increase at predetermined points along the length of the film. This is efiected by moving the shutters I5 and I6. selectively across the apertures l2 and I4, through the medium of grading strips -II and I8 of very thick paper formed respectively with cam edges "and 24 that act on levers 2| and 22 connected to the shutters II and Supposing the sound represented by the track I 50 is to increase to the maximum possible mean volume, while the sound represented by the track I is to fade out completely, the shutter I4 is moved downwards, as viewed in Fig.2, so as to expose the whole of the aperture I! to its associated light 55 source 23. Thus, the whole width of therecord on thefilm Sisprinteduponthefilm I andoc-. copies the space between the lines 4 and II. A trifle later, the shutter l3 is'moved downwardly so as toobscure the whole of the aperture l4 from 00 its associated light source 24.

The cam edges l3 and 23 may be complementary. Then, the widthof the exposed part of the aperture l2 plus the width of the exposed part of the aperture I4 is always equal to the perpen- 65 dicular distance between the lines 3 and I4.

- 73 the grading strips I I and I4 are run at a lower I controllable aperture i4. As shown in Fig. 2, each' vertical spindle 43.

speed than the film I both for the purpose of economy in the paper from which the grading strips are made, and for the purpose of avoiding too steep changes in the contours of the cam edges I3 and 20. v

To prevent'the grading strips I1 and 18 from twisting as they pass the rollers 25 and 26, each grading strip is drawn between the pair of plates 21 and 23, the plates 21 and 23 respectively engaging the upperand lower faces of the strips 0 I I and I 8. These plates are formed with slots 23 that are traversed by the rollers 25 and 26 as they are swung in accordance with the configurations of the cam edges l3 and 30.

The apparatus of Figures 1 and 2 is only suit- 15 able for printing variable density sound tracks but the apparatus of Figures 3 to 5 may be used either for variable density tracks or variable area tracks. In fact, a great advantage of the last mentioned apparatus is that it can be used in the production of a composite sound track comprising variable area and variable density tracks side by side. A variable area track is, of course, one which, in the negative, is a transparent strip that has one edge in wave form representing the sound.

In the apparatus of Figure 3, the film 30 being exposed to have sound tracks printed thereon is drawn down from a bobbin 3| by a bobbin 32 driven by an electric motor indicated generally by the reference numeral 33. One of the sound 30 tracks is. printed on the filni 30 from a sound track on a film 34, which is withdrawn from a bobbin 35 by a bobbin 36 driven by an electric motor indicated generally by the reference numeral 31. Y 35 A beam of light from a source 38 passes through the sound track onthe film 34 and is concentrated on the film 30 by a lens system indicated generally by the reference numeral 33. This system is as free as possible from chromatic and spherical 4 aberration and has a long focal length so that, in the operation of the apparatus as described below, the image of the sound track on the film 34- is formed upon the film 30 substantially free from unwanted distortion. The bobbins 35 and es 36 are pivotally mounted between arms 43 and 4i extending upwardly from a turntable 42 fixed to a When this turntable is turned about the axis A-A of the spindle 43, the vertical plane of the film 34 is turned relatively to the film 33 and to the beam of light. The motor 31 which drives the bobbin 36 is mounted on-the turntable 42, so that when thelatter is turned the motor 31 moves relatively to the motor 33. It is. however, necessary for the motors 33 and 31 to run exactly in phase and, owing to the relative movement of the motors, a. mechanical connection between them is not very convenient. Accordingly, the motors 33 and 31 are induction motors connected to run in accordance with the well known self-synchronising system. Thus, the motors have rotors with three phase windings, indicated inFlgure 3 by the star windings 44. The stators (not shown) of these motors are connected to a sourceof alternating current and are wound to provide a rotating magnetic field which serves to rotate the rotors. In order that the latter may run precisely in phase, the ends of the star windings 44 are connected, as shown, by conductors 43 which are connected together by resistances 43. The flexibility of the conductors 45 enables the motor 31 to move relatively to the motor 33.

Sections through the films 30 and 34 appear in Figs. 4 and 5, and the sound track on the film 7s =d The Figures3to5mayhealmliedinthe slightly moai- 34 is indicated in thoseflgures by lines 41. The imagejotthis sound track on the film it is indicated by lines 48 in Figures 4 and 5. From Figure 4 it will be seen that, when theplane of the 5 strip this at right angles to the-optical axis, the width or the image 48 is always equal to the width of the track l1. When, however, the tumtable 42 is turned from the position of Figure 4 to a position such as that shown in Figure 5, lo the width of the image 4| is reduced. However, owing to the position ofthe axis A--A oi the turntable 42, when the image 48 is reduced in width, its edge 4! remains in aconstant position on the strip SI. Thus, as the track ll is being is printed on the strip a. the turntable 4: may be swung to-and-iro about the axis A -A to increase and decrease the width or the track 48 and alter the mean volume of sound'available from that track along its length. Also, the re-' duction 'of the width of the track ll leaves a space for a second track. This second track is printed by passing the film ll past a second optical system 38', I8, and a'second turntable arrangement bearing asecond film ll with the other 2 sound track recorded thereon. This second film 3 This modulation controls photo-electric It and- I which are connected respectively to potentiometers It and 01. These potentiometers are connected, as shown, toa loudspeaker 08.

Thus, the sounds recorded-on the sound tracks g Q of the films It and I are mixed and reproduced simultaneously by the loudspeaker ii. In practice, or course, an amplifier. is interposed between the loudspeaker and the potentiometers. Assuming that the strip il bears a record-of speech ll 7 and the strip ti, bears a records! music, the

volume or speech emitted from the loudspeaker 68 in relation to the volume or music depends upon the setting or the brushes it and "in the potentiometers relatively to their respective rei8 sistances 1i and I2. As the-strips I and ii are rim past the photo-electric devices, the operator turns dials l3 and 14 connected respectively by shafts II and It to the brushes ill and II so as to bring the volumes of the sounds to the relative ll values that he thinks desirable along the length or the films so and ii. The operator will do this several times and willmake notes .0! the settings of the dials I! and It in relation to points along the lengths oi the films u and u. He is enabled so 34' is withdrawn from a'bobbin 35' by a bobbin to note these points by counters, not shown, op-

38 driven by a motor 31' connected as shown to rotate in synchronism with the motors" and ll.

The axis of this second turntable is arranged so 30 that, when the turntable is rotated to vary the width of the image of the second sound track, one edge of that image always remains on the vertical line represented by the point It in Figure 4. Thus, except when the second sound track 5 is tadedout completely to makezway for the full volume of the first sound track, the turntable 42, associated with the first sound track, would never be in the position of Figure 4 but would always be in a position such as that shown in-l lsin'co 40 to leave-room for the second sound track.

a The turntables used in the method described above with reference to Figures 3 to 5 may be 7 turned under the control of grading strips like those shown in Figure 2. Then, the width of each sound track is automatically controlled in accordance with a cam contour. Referring to Figure 3, it will be seen thatgrading strips i1 and II formed with cam edges is. and ll are caused to travel past rollers 25' and 26' at the go ends oi arms llfand 22' secured respectively to the spindles 43 and 43? o! the turntables II and 42'. Thus as the strips l1 and i0 traverse the rollers 25' and It, the levers 2| and 22' are oscillated in accordance with the formation of the as cam edges II and II and the angular positions of the turntables, and consequently the widths oi the imagesbeing printed on thefilm "are varied precisely'in accordance with the cam conprinciples inherent in the apparatus of fiedmannershowninFigureiLwherethepime or the film ll is kept stationary and the optical system together with the film 3| are mounted on iaturntablellmsoastoswing'aboutanaxis to vary the width oi-the im -projected on strip 3..

One method by which the gradirgv strips may be produced isbyusing the monitoringapparatus 1o inFigurcl. Theoperstoniniuingtheanparlms of Figure 'L causes two strips od illm II and ii, which may be regarded, tor-example, as the strips otfilmiandtinl'igmehto verse erated by the strips I and ti. When he has determined and noted the desired settings of the potentiometers Ii and 12 at the various points along-the lengths'oi the films and I he con- I! nects the shafts 1i and It to shafts I1 and II. He then runs the strips of filmJl and ti past the photo-electric devices 64 and Cl once more. Simultaneously, he runs a strip ll of still. paper The strip 88 beneath rotating cutters II and ti. I9 travels in timed relationship with the films ll and Bi but at a reduced rate or travel. Assuming the films I. and II are to be thefilms'i and 6 cl. Figure 1, this rate of travel bears the same relationship to the rate of travel of the films 40 it and I as that borne'by the-strips i1 and II to the films 5 and i. The printing and, therefore. the speed of the films i and i may be slower than the speed at which the films are run (or the reproductionot sound. As the three strips ll, ii 45' and I! are passed through the apparatus of Figure '7, the dials It and "are turned by the oper-,

atom" inaccordance with his notes so that the past-the photo-electric devices Cl and CI, but

in that event the operator will not hear the relative volumes to be obtained when the master negative-ot the two-sound tracks is printed in accordancewiththecamedgesbeingtormedbycuttimfl the strip It. Also, a counter mustbe operated bythestrip'llsothsttheoperatorcansetthe dials II and "in accordance with hisnotes. 'l'hiscounter indicates the pointsonthestrip II which correspond to the polntsalong the strips Q! It and Ii.

'I'heasiaimovementoithecuttersllandll is 1 transmitted from the'shaits I1 and II throwh the levers I4 and it having forked end which ensasediscsltandtlfixedtotheshsitslland I! that'csrry the cutters u: and II.

Insteadoi the'circular cutters t0 and II, rretsaws-may be used for severing the papa-strip II. 'where complementary grading strips are requirfl asinglecutieronly-isusedandthiscutstbestflp-rg it will be clear that such apparatus can be extended for printing three or more sound tracks,'

if desired.

I claim:

1. A method of producing a record of sounds on a cinematograph film, which comprises'the stems of printing a sound track on said film by projecting a beam or light through a sound track already recorded on a further film to cast an image of said track on said first-mentioned film, while selectively adjusting the angle subtended by the planes of one of said two films relatively to the axis ,or said beam to .vary along its length the width of said track being printed, and printing a further track on said film closely adjacent said first-mentioned track.

2. A method of producing a record of sound on a cinematograph film, which comprises the steps of printing a sound track on said film while varying the width of said-track and printing a second track on said film closely adjacent said first track while varying the width of said second track,

thewidths of each of said tracks being controlled along its length by a grading strip caused to travel in timed relationship with said film.

3. A method of producing a record of sounds on a cinematograph film, which comprises the steps or printing parallel and closely adjacent sound tracks on the said film while the latter travels in timed relationship with grading charts formed with cam edges, and varying the widths oi said sound tracks along their lengths in accordance with said cam edges.

4. A method of producing a record of sounds on a cinematograph film, which comprises the steps of forming a grading chart with a cam edge by severing said chart from a wider strip as the latter traverses a cuttermoved to-and-fro across said strip in accordance with the relative production, printing a sound track on said film while the latter travels in timed relationship with said grading chart, varying the width of said track along its length in accordance with said cam edge, and printing on said film a second track closely adjacent said first-mentioned track.

5. A method of producing a record of sounds on a cinematograph film which comprises the yolumes of said sounds desired during their resteps of printing a sound track on said film by projecting a beam of light through a sound track already recorded on a further film to cause an image of the track on said first-mentioned film, printing a second sound track on said first-mentioned film by projecting a beam of light through a sound track already recorded on a third film to cause an image of the second track closely adjacent said first-mentioned image and selectively adjusting the angle subtended by the planes of said two films bearing tracks already recorded relatively to the axes of said beams to vary along their lengths the widths oi the tracks being printed.

LEWIS CHARLES RUDKIN. 

